HOWTO AIX: FUNCTION KEYS BEHAVING ERRATICALLY
ITEM: RTA000037063
PRODUCT:
AIX FOR RISC SYSTEM/6000 Version 3 Release 2 Modification 0
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** This HOWTO item was written and tested with the above operating **
** system(s). The provided explanations, techniques and procedures**
** have been reviewed for technical accuracy and applicability. **
** Though the techniques and information contained in this item **
** may work on other levels of the operating system(s), it has not **
** necessarily been tested. Normal precautions should be taken in **
** adopting these same techniques and procedures in your own **
** environment. **
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SCENARIO/EXPLANATION:
Two RISC/6000s running X.25 are connected through a packet switching
data network (PSDN). The remote user telnets to the central site
and tries to use our function key-driven application. Unfortunate-
ly, the function keys behave erratically -- often just refreshing
the screen as it would if only the ESC key were pressed. If,
however, the remote user accesses the SMIT application, the function
keys work properly.
The function keys also work correctly when users telnet in across
the Token-Ring and access the application.
SOLUTION:
The function keys generate a multibyte escape sequence. In your
case, the escape sequence is being split between two TCP/IP data-
grams and that, coupled with the comparatively slower response time
of packet switching, is causing the system to misinterpret the
sequence. The following is an excerpt from InfoExplorer entitled
"Telnet or rlogin Problems in TCP/IP"
"Problems with function and arrow keys may arise when using rlogin
and telnet commands with programs using extended curses. Func-
tion and arrow keys generate escape sequences, which are split if
too little time is allotted for the entire key sequence. Curses
waits a specific amount of time to decide whether an ESC
indicates the escape key only or the start of a multibyte escape
sequence generated by other keys, such as cursor keys, the action
key, and function keys.
If no data, or invalid data, follows the ESC in the allotted
amount of time, curses decides that the ESC is the escape key and
the key sequence is split. The delay resulting from the rlogin
and telnet command is "network dependent." Sometimes arrow and
function keys work and sometimes they do not depending on the
speed of the network to which you are connecting. Setting the
ESCDELAY environment variable to a large value (1000 to 1500)
effectively solves the problem."
Therefore, try setting ESCDELAY to a very high value as follows:
1. Insert the following in /etc/environment:
ESCDELAY=5000
2. Log completely out of the system, then back in to make sure
the new ESCDELAY value is set.
3. Verify via the following command:
echo $ESCDELAY
Once your test is completed, remember to either adjust the value
down to a more reasonable value (between 1000 and 2000) or, if
your problem is not resolved, remove this line completely from
the /etc/environment file.
If setting this ESCDELAY parameter doesn't fix your problem, then
your application is not written to extended curses and the applica-
tion and must be modified to await the entire escape sequence. For
example, the AIX SMIT application is written to curses, but it will
work over a slow network regardless of ESCDELAY because SMIT was
written to wait indefinitely for the entire escape sequence. Thus,
even though the "iptrace" tool clearly shows the separation of the
ESC and the remainder of the escape sequence, the escape keys work
correctly in SMIT.
REFERENCES:
- AIX V3.2 X.25 Communications Cookbook (GG24-3692-01, page 103.
- AIX/6000 product documentation.
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This item was created from library item Q649383 NNJS6
Additional search words:
$$A ACROSS AIX ALTERNATE BEHAVING COMMUNICATIO DEC93 ERR ERRATICALLY
ERROR EXECUTING FUNCTION FUNCTIONAL HOWTO INCORRECT INDEX IX KEYS
NNJS6 PSDN RISCSYSTEM RISCTCP RLOGIN SOFTWARE TCPIP TELNET X.25 X25
WWQA: ITEM: RTA000037063 ITEM: RTA000037063
Dated: 04/1996 Category: RISCTCP
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